This suggests that most (if not all) SNIa contributing to the enrichment exploded not much later than the peak of cosmic star formation [1]}. Several studies of the SNIa delay-time distribution in fact support this picture, finding that a significant number of such explosions occur as early as 100 Myr after a star formation event ([2]}, [3]}; for a review on SNIa delay-time distribution and its interpretations, see [4]}).
